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1468 Correspondence JACC Vol. 61, No. 13, 2013April 2, 2013:1461–8

missed MIs represent a major cause of legal liability. Similarly, theadvice to interpret an elevated troponin level in the clinical contextis wise, yet may have a limited effect—estimates of pre-testprobability have a high interobserver variability (3). Physiciansoften do not make formal quantitative calculations in practice (4)and make errors when they do (5).

Troponins, as currently used, have an excellent negative predic-tive value, but poor positive predictive value. The absolute value oftroponin and the degree of increase on sequential testing arehelpful in diagnosing acute MI, but may be less helpful inconfirming thrombotic ACS as the cause. We have observed casesof acute troponin I increases as great as 10 ng/ml with stroke, diabeticketoacidosis, and heart failure. As the key therapeutic decision toprovide antithrombotics or urgent revascularization usually occurs onpresentation, and such therapies can only benefit patients withsignificant ACS, practicing clinicians need a second confirmatory testfor ACS. Such a test should be less severely affected by sepsis,tachyarrhythmia, hypotension, renal failure, chronic coronary disease,demand ischemia, heart failure, or cardiomyopathy, even if it isinsensitive to small amounts of myonecrosis. That test, arguably, is thecreatine kinase–myocardial band and index.

*Arnold Seto, MD, MPADavid Tehrani, BS

*University of CaliforniaIrvine Medical Center101 The City DriveOrange, California 92868E-mail: [email protected]

http://dx.doi.org/10.1016/j.jacc.2013.01.045

EFERENCES

1. Newby LK, Jesse RL, Babb JD, et al. ACCF 2012 Expert consensus
document on practical clinical considerations in the interpretation of
troponin elevations: a report of the American College of CardiologyFoundation Task Force on Clinical Expert Consensus Documents.J Am Coll Cardiol 2012;60:2427–63.

. Waxman DA, Hecht S, Schappert J, Husk G. A model for troponin Ias a quantitative predictor of in-hospital mortality. J Am Coll Cardiol2006;48:1755–62.

. Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. The rationalclinical examination. Is this patient having a myocardial infarction?JAMA 1998;280:1256–63.

. Reid MC, Lane DA, Feinstein AR. Academic calculations versusclinical judgments: practicing physicians’ use of quantitative measures oftest accuracy. Am J Med 1998;104:374–80.

. Steurer J, Fischer JE, Bachmann LM, Koller M, ter Riet G. Commu-nicating accuracy of tests to general practitioners: a controlled study.BMJ 2002;324:824–6.

Reply

The American College of Cardiology Foundation (ACCF) wel-comes letters to inform its ongoing work and encourages suchcorrespondence about its clinical policy statements. Because theACCF document development process is rigorous and involvesseveral layers of review by the writing committee, external peerreviewers, and participating organizations in the document, itcannot respond to each issue raised after a document has beenpublished. The information, however, is forwarded to the WritingCommittee co-chairs and oversight Task Force for review. If anyissues are deemed by the College to affect patient safety, they willbe considered immediately. Otherwise, the information will beconsidered during the next revision of the document.

*The American College of Cardiology Foundation

*American College of Cardiology2400 N Street, NWWashington, DC 20037


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